Method and apparatus for decapping integrated circuit packages

Abstract

The invention relates to a method and apparatus for decapping integrated circuit packages. The invention involves irradiating an IC package with laser radiation, typically in the UV-IR spectra and of short pulse duration. The irradiation results in ablation of the molding compound. The invention also provides real-time monitoring and process control of the decapping process and fluid-flow removal of ablation debris. Using the invention, decapping can be performed without causing damage to the internal IC structure. Furthermore, decapping in a liquid can prevent oxidization of the molding compound by ambient air.

1. A method for decapping an integrated circuit package ( 1 ), the package ( 1 ) comprising one or more layers of electronic circuitry covered by one or more layers of capping material ( 6 ), characterized in that the method includes the steps of immersing the integrated circuit package in liquid during the decapping process and irradiating the integrated circuit package ( 1 ) with laser radiation so as to remove the capping material ( 6 ). 
     
     
       2. A method according to  claim 1  including the step of selecting ( 30 ) a selected location on the integrated circuit package to be irradiated before performing the irradiation step ( 31 ). 
     
     
       3. A method according to  claim 2  wherein the method further includes the steps of monitoring ( 35 ) the decapping process; determining ( 36 ) whether decapping is complete at the said selected location; if the above determination is negative, continuing to irradiate ( 31 ) the integrated circuit package and if the above determination is positive, determining ( 37 ) whether all decapping is complete; if all decapping has been determined to be complete, stopping ( 38 ) the decapping process, and if all decapping has not been determined to be complete, selecting ( 39 ) a new location at which the laser energy is to be directed and continuing to irradiate ( 31 ) the integrated circuit package. 
     
     
       4. A method according to  claim 3  wherein the said determination ( 36 ) as to whether decapping is complete at the said location involves the monitoring of acoustic and/or optical signals emanating from the decapping location. 
     
     
       5. A method according to  claim 1  further characterized in that it includes the steps of ( 32 ) measuring the energy of the laser radiation; ( 33 ) comparing the measured energy of the laser radiation with an expected value and ( 34 ) adjusting the laser energy accordingly if the two values do not correspond. 
     
     
       6. A method according to  claim 1  characterized in the further step ( 29 ) of causing a fluid ( 19 ) to flow over the integrated circuit package ( 1 ). 
     
     
       7. A method according to  claim 6  wherein the said fluid ( 19 ) is a liquid. 
     
     
       8. A method according to  claim 6  wherein the said fluid ( 19 ) is a gas. 
     
     
       9. The method of  claim 1  wherein the liquid is water or Isopropyl alcohol. 
     
     
       10. The method of  claim 1  further comprising, after immersing the integrated circuit package, initiating a flow of the liquid over the package to remove debris in the liquid flow. 
     
     
       11. A device for decapping an integrated circuit package, the integrated circuit package ( 1 ) comprising one or more layers of electronic circuitry covered by one or more layers of capping material characterized in that the device comprises a source ( 6 ) of laser energy and means ( 21 ) for holding the integrated circuit package; a source of liquid for immersing the integrated circuit package in the liquid ( 19 ) during the decapping process; the integrated circuit package being irradiated by the laser energy so as to remove the capping material. 
     
     
       12. A device according to  claim 11  wherein means ( 9 ,  10 ,  11 ) are provided to monitor the said laser energy, compare the monitored value with an expected value and adjust the properties of the laser source ( 6 ) accordingly. 
     
     
       13. A device according to  claim 11  wherein means ( 25 ,  11 ) are provided to monitor the laser decapping process. 
     
     
       14. A device according to  claim 11  wherein means ( 23 ,  24 ) are provided to provide an image of the integrated circuit package during the laser decapping process. 
     
     
       15. A device according to  claim 11  wherein means ( 20 ,  21 ) are provided to generate a flow of fluid ( 19 ) over the integrated circuit package during the decapping process. 
     
     
       16. A device according to  claim 11  wherein means ( 22 ) are provided to effect relative movement between the laser energy directed at the integrated circuit package and the integrated circuit package itself, whereby different locations on the integrated circuit package may be irradiated. 
     
     
       17. The device of  claim 11  wherein the fluid is water or Isopropyl alcohol. 
     
     
       18. The device of  claim 11  further comprising a flow source for initiating a flow of the liquid over the integrated circuit package to remove debris from the integrated circuit package in the liquid flow.